Soluble oil composition



SOLUBLE OlL COMPOSITION George R. Cook, Crystal Lake, and Allan Manteufliel,

Union, 11]., assignors to The Pure Oil Company, Chlcago, 111., a corporation of Qhio No Drawing. Application December 30, 1952, Serial No. 328,804

11 Claims. or. 2s2--s3.3

This invention relates to the art of cutting metals and is specifically concerned with an improved soluble or emulsifiable cutting oil composition. This application is a continuation-in-part of application, Serial Number 234,- 910, filed July 2, 1951, now abandoned.

The use of cutting fluids in conjunction with metal working operations, to facilitate thev various machining operations on the metal, developed from the discovery that water when used as a coolant in a metal turning operation permitted higher speed operation. lVhen the need for lubricating characteristics in the cutting oil arose, simple compositions were formulated from animal, vegetable, and mineral oils. Modern metal working operations, such as drilling, boring, milling, reaming, turning, etc., require more versatile fluids which will not only function as Coolants but which will provide lubrication needs whichare necessary when the metal working tool is in contact with the metal being worked.

To provide these multifunctional characteristics complex mixtures of compounds have been developed. Metal cutting fluids are classified compositionwise as straight oil cutting fluids and soluble oils or compounds. The former are employed neat at the machine and require no special precautions in their application. The latter are mixed with water to form an emulsion or solution for, use at the machine. Although the soluble oil type requires careful selection, proper preparation of emulsion. and maintenance in service, there are specific machining operations, particularly where cooling is the predominant requirement, in which this type of fluid is best employed. Such operations include grinding, milling, boring, reaming, and drilling. These soluble cutting oils have particular application in high speed machining operations and are also employed when brittle materials, such as cast iron, are being worked. Furthermore, soluble oils are more desirable than straight oils for specific metal turning operations because they are cleaner and their films are more easily removed from the machined product.

The soluble oils are supplied to the machine shop operator as a mixture of a mineral oil containing an emulsifiable base or soap plus a coupling agent or stabilizer. Although generally referred to as soluble oils, and this nomenclature will be followed in describing the instant invention, these materials when mixed with water ordinarily form an emulsion. In order to distinguish between the soluble oil mixture in its concentrate form and the emulsion which is produced when this concentrate is admixed Withsufficient quantities of water, the former mixture will be referred to in describing this invention as the soluble oil blend and the latter composition will be termed the soluble oil emulsion. The emulsion which is formed when the soluble oil blend is mixed with water is an intricate colloidal system of the oil-in-water type wherein the aqueous phase constitutes the continuous or dispersing phase and the mineral oil constituent is the dispersed phase.

A third and separate phase may be described as the oil-water interface which is the sum or the result of a ice 2 delicately balanced chemical composition, partially soluble in the oil and partially soluble in the water phase. In the formulation of these soluble oils, considerable emphasis is placed .upon the uniformity and the stability of the soluble oilemulsion. An emulsion .is a delicately balanced system and the components of the soluble oil blend are chosen with concinnity'in order to insure conformance with the desirable characteristics. The emulsifier may consist of sulfonates, acid sludges, saponified phenols or naphthenic acids, sodium and potassium rosin soaps, amine soaps of rosin acid, etc., either alone or in combination with these or other emulsifiers. Because of theirefiectiveness as emulsifiers, sulfonates. are preferred. To supple ment the emulsifier used, itfrequently-is advantageous to employ extenders. This expedient permits adequate emulsification of the soluble oil with lesser amounts of emulsifier. An example of an extender which may be employed in conjunction with the petroleum sulfonates is. a liquid mixtureof sodium or potassium salts of various processed rosins and resins, such as sodium resinate. The mineral oil component is generally a medium viscosity petroleum oil. This type of oil includes oils having various geographical origins such. as Pennsylvania, Gulf Coast, and California. Although most oils may be used as the mineral oil constituent, Gulf Coastal oils are particularly acceptable. Also included as a component of the soluble oil blend is a coupling agent or stabilizer in the form of an alcohol, such as ethyl alcohol, or a polyhydroxy alcohol, such as ethylene glycol. This coupling agent, which is mutually soluble in the continuous phase and in the dispersed phase of the emulsion, functions to stabilize these two phases. In order to assist the coupling agent in providing a stable oil-in-water emulsion, control of the pH of the cutting oil emulsion is necessary. This control of the acidity of theoil-in-water emulsion, which is produced when the oil blend is added to water to produce the desirable cutting fluid, is brought about by the inclusion of a fatty acid, .such as oleic acid, and an alkali, such as sodium or potassium hydroxide, as constituents of the soluble oil blend. It is this combination which controls the balance of the third phase hereinbefore referred to as the interface between the oil droplets and the water. Thiscombination also permits the use of the soluble oil blend in both hard andsoft waters in theformation. of the:

finishedemulsioni Where heavy duty cutting oils are desired, sulfurized or chlorinated E. P. agents may constitute part-of thesoluble oil blend. Rust inhibitors, germi'cides,

foam depressants, and additives for freeze-thaw stability may also be advantageously employed as ingredientsin the composition i As it hasbeenpointedout, in order to achieve a stable oil-in-water emulsion, it is necessary to formulate, the,

soluble or emulsifiable oil in such a manner that the components are maintained in a very delicate balance,

relative to the chemical and physical properties of the blend and emulsion. By carefully blending the typesand quantities of the constituents of the soluble oil blend, stability ofthe oil'blend as well as a stable oil-in-water emulsion is provided. A typical soluble oil blend which meets the foregoing requirements of stability as well. as functioning as a coolant and lubricant in. various machining operations has the following formulation:

It will be noted-that this formulation employs as the mineral oil constituent a medium viscosity Gulf Coast oil. In the production of these metal cutting fluids, it is desirable that some flexibility be available in their formulation in order that economic conditions and short supply of the constituents will not necessarily handicap the manufacturer of cutting fluids. For that reason, it has been necessary to investigate various combinations of ingredients for use in soluble oil blends. As potential substitutes for the Gulf Coastal oil, Mid-Continent oils, and residual extracts produced in the refining of lubricating oils have been tested. However, many difficulties have been observed when attemptshave been made to substitute these materials for Gulf Coastal oils in the preparation of soluble oil blends and soluble oil emulsions. It has been discovered that direct substitution of a Mid- Continent solvent refined oil or a solvent extract for the Gulf Coastal oilsof the above formulation results in a number of undesirable characteristics in the soluble oil blend and in the soluble oil emulsions formed from the soluble oil blend. Among the major difficulties encountered are the instability of the soluble oil blend and the soluble oil emulsion, and other difiiculties arising from the unbalancing of the delicately formulated soluble oil liquid contact with the selective solvents employed in the various solvent refining processes which are an integral part of petroleum oil refining operations. Examples of processes which produce suitable extracts include the Duosol process, furfural process, phenol extraction process, Clorex process, and other solvent extraction processes which are employed to increase the viscosity index of the desired raflinate product. The extract from these processes contains a high proportion of aromatic hydrocarbons and, although it is thought that the aromaticity of these extracts influences their stabilizing effect on soluble oil blends and emulsions, this is a postulation, and this concept should not limit the present invention. The characteristics and properties of solvent extracts suitable for use in accordance with the present invention are listed in Table I below. In the interest of simplicty and in order to render direct comparison of formulations possible, Extract No. 1 of Table I, which is a phenol extract obtained from a 100 viscosity neutral oil, has been employed in the specific examples set forth herein. However, it is to be understood that other extracts listed may also be used, and that the selection of this particular extract for the specific examples is not to be construed as limiting:

TABLE I Physical properties of phenol extracts API Vis/100 Vis/130 Visl2l0 Pour, Percent Percent Extract No Gravity F. F. F. V. 1 F. Carbon Sulfur Residue (Ext.) (Ext) (min.)

blend by attempts to replace the mineral oil component thereof.

It is, therefore, an object of the present invention to provide improved soluble oil blends and soluble oil emulsions.

Another object of the present invention is to provide soluble oil blends which emulsify readily in both hard and soft water and which form stable emulsions with such waters.

Another and further object of this invention is to provide soluble oil blends and soluble oil emulsions utilizing inexpensive mineral oil components.

Still another object of this invention is to provide highly stable soluble oil blends and soluble oil emulsions containing Mid-Continent solvent refined Oils and/or residual solvent extracts. These and other objects will be apparent from the following description of this invention.

In accordance with this invention, it has been found that when a residual extract which is produced in the solvent refining of lubricating oils is made a component of the cutting oil blend employing a Mid-Continent solvent refined oil, exceptional blend stability and emulsion stability properties are obtained. The extracts which are employed in this invention heretofore have not been very widely used as they have been considered to contain the extracted undesirable constituents of a lubricating oil base stock. These extracts are produced as a residual product when a lubricating oil base stock is contacted in liquid- Table II shows a tabulated summary of results which indicate the trends found by varying the proportions of Mid-Continent solvent refined neutral oil and residual extract in a soluble oil blend containing the following ingredients as the emulsifying portion of the blend:

Breakdown of emulsifying portion Constituent: Weight percent Mahogany sulfonate 10.06 Commercial oleic acid 2.01 Diethylene glycol 1.64 Potassium hydroxide 0.34 Water 0.95

In this emulsifying portion the mahogany sulfonate was employed as the emulsifier and the diethylene glycol was employed as the coupling agent. The oleic acid and potassium hydroxide were included as constituents of the soluble oil blend to control the acidity of the oil-in-water emulsion which is produced when sufiicient water is added to the soluble oil blend to produce the desirable cutting fluid. It is this combination which controls the balance of the third phase hereinbefore referred to as the interface between the oil droplets and the water which is the dispersing medium. This pH control of the cutting oil emulsion is necessary in order to assist the coupling agent in providing a stable oil-in-water emulsion.

Inf a the extract from a phenol extraction process is preferred because the extracts thus obtained contain small quantities of phenol. This phenol content adds germicidal properties to thesoluble oil blend and fortifies the blend against putrefaction of the emulsion. It is'also preferred to employ a phenol extract which is obtained from solvent extraction of neutral oils since the extract which is obtained in solvent processing a bright stock has an extremely high viscosity. This high viscosity cannot be tolerated in the soluble oil blend. However, it is possible to employ'kerosene as a cutback to lower the viscosity of phenol extract obtained in treating bright stock oils. The resulting mixture can then be added to the mineral oil portion in the compounding of satisfactory soluble oil blends.

It is to be observed that-best results are obtained in the formulation set forth above by employing equal amounts of a Mid-Continent solvent refined oil anda residual extract. Although this composition is preferred, Table II illustrates that quantities of residual extract as high as 75 per cent by weight of the soluble oil blend and as'low as per cent by weight also improve the stability of the soluble oil blend and the emulsion formed therefrom. It may also be seen by a review of Table II that stable soluble oil blends and soluble oil emulsions cannot be obtained when residual extract is employed as the sole mineral oil component of the blend. However, it has been found that this diificulty can be overcome byeliminating oleic acid from the soluble oil' blend shown above. Thus, it has been found that the addition of oleic acid to soluble oil blends containing residual extracts as thes'ole mineral oil component of the blend,'results in a maladjustment of the delicate balance of the soluble oil blend and reduces the efiectiveness of the coupling agent in providing stable emulsions from such blends. It'is, therefore, possible to formulate a soluble oil blend of improved emulsion stability with both hard and soft waters and soluble oil blends and emulsions of greater stability by eliminating oleic acid from the soluble oil blend and employing residual extracts as the sole mineral oil component. The following generic formulation can beused as a soluble oil blent; when oleic acid is eliminated from the previous soluble oil blend.

Constituent: Weight percent Emulsifier, coupling agent, Water 10-50 Residual extract 50-90 More specifically, a soluble oil blend having the following constituents is preferred:

TABLE II Mineral Oil Portion Emulsion Stability Emulsifying Mid-Oon- Blend 1 Portion tinent; Stability Solvent Residual 1/10 11/20 1/15 Refined,v Extract: 100 Vis. at

Nil Failure Failure Failure Failure. 63.7 21.3 Pass Good Good air. 42.5 42.5 do Exeelleil1;-. Excellent Excellent. 21.3 63.7 -do ood. Good. Fair. Nil 85 0 {5322:2 59 F Failure Failure Failure.

1 Observed at 32 F. and 72 F. for two weeks. 2 Emulsion ratios given in ratios of one part otoil blend to total parts of. water and oil, i.-e., l/l0=1 part oil blend in 9 parts of water. t a

It is, therefore, seen that by employing a residual ex- 20 Constituent: Weight percent tract as a constituent of the mineral oil portion of the Mahogany s'ulfonate' 11.5 soluble oil blend it is possible to utilize a Mid-Continent Diethylene glycol 1.5 solvent refined oil in a soluble oil blend and obtain sta- Water 1.5 bility of the blend and emulsion which is not otherwise Residual extract 85.5 obtainable. Although various extracts may be employed, I

As has been pointed out heretofore, in order to obtain a suitable emulsion when a soluble oil blend is'mixed with'water and toobtain-blends which will form emulsions in either hard or soft waters, the acidity'of the blend shouldbe delicately adjusted. Ordinarily, the acidity of the soluble oil blend is adjusted so that a blend having a neutralization value ranging from a base number of 6.0 to-an acid number of 3.0, as'measured by ASTM method D974-51T, will be obtained. The ASTM method referred 'toisthe Tentative Method of, Test for Neutralization Value (Acid'and Base Numbers) by Color-Indicator Titration issuedin 1948 and revised in l951,'and will be referred to hereinas the ASTM 1948 method. In some cases, it has been found that the acidity of the finished soluble oil blend does-not fall within this preferred range when residual extract alone is used as the mineral oil component. This depends upon the quantity and nature of the extract employed. It has been found that this situation may be remedied by-adding sufficient solvent refined neutral mineral oil to the blend to dilute theblend and =thus'obtain a finished blend having the desired acidity.

-In general, up to about 25 per cent of neutral mineral oil will besuflicient to bring the acidity of a finished emulsion within the range of a base number of 6.0 to an acid numberof 3.0. In lieu of or in addition to the neutral mineral oil, small amounts of an alkali such as potassium hydroxide or sodium hydroxide may be employed. It has been found that from about 0.01 to 1.0 per cent by weight of an alkali is suflicientto obtain the desired neutralization value in the soluble oil blend. Specific formulations employing small amounts of solvent refined neutral oil and/oralkali in addition to the residual extract, would contain the following constituents:

Constituent: Weight percent Mahogany sulfonate 11.5 Diethylene glycol 1.5 Water 1.5 Residual extract 64.5 Mid-Continent solvent refined neutral oil 21.0 Mahogany sulfonate 11.5 Diethylene glycol 1.5

Water 1.5

Alkali 0.32 Residual extract 85.18

Highly stable soluble oil blends having the following ingredients may also be formulated by employing an emulsifier extender to supplement the emulsifier:

Constituent: Weight percent Mahogany sulfonate 6.5 Sodium resinate 5.0 Diethylene glycol 1.5 Water 1.5 Residual extract 85.5

Mahogany sulfonate 6.5 Sodium resinate 5.0 Diethylene glycol 1.5 Water 1.5 Mid-Continent solvent refined neutral oil 21.0 Residual extract 64.5

Mahogany sulfonate 6.5 Sodium resinate 5.0 Diethylene glycol 1.5 Water 1.5 Alkali 0.32 Residual extract 85.18

It is to be understood that the amounts of emulsifier, emulsifier extender, coupling agent, and water which are listed in the specific examples contained in this specification are not to be construed as limiting, but that any suitable quantities of these materials may be employed. For example, when the emulsifier is used without an emulsifier extender, amounts as low as 9 per cent by weight of the blend and as high as 50 per cent by weight may be employed. However, economic considerations ordinarily dictate that the amount of emulsifier should be substantially below the upper limitation of 50 per cent. When an emulsifier is used together with an emulsifier extender, the minimum concentration of emulsifier should be about 6.0 per cent by weight and the amount of extender at least about 3.5 per cent by weight. The minimum requirements'for water in the formulations of this invention may be as low as about 0.25 per cent by weight of the soluble oil blend, while the minimum requirements for coupling agent may be as low as about 0.5 per cent by weight.

What is claimed is:

1. A soluble oil blend consisting of a mixture of the following ingredients:

Constituent: Weight percent Sodium mahogany sulfonate 9.050.0 Diethylene glycol 0.5- 2.5 Water 0.25- 2.5 Caustic 0.01- 1.0 Phenol extract 50.0-90.0

said phenol extract being obtained from the solvent extraction of a Mid-Continent neutral lubricating oil by treatment with a solvent which removes as an extract phase a predominance of aromatic hydrocarbons, said soluble oil blend being characterized by having a neturalization value ranging from a base number of 6.0 to an acid number of 3.0 as measured by the ASTM 1948 method and further characterized by its stability when emulsified with both hard and soft water for use as a cutting oil lubricant.

2. A soluble oil blend in accordance with claim 1 in which the phenol extract has an API gravity of about 13.3, a viscosity at 100 F. of about 340 SUS, a viscosity index of about -32, a pour point of +35 F., a carbon residue of about 0.13 and a total sulfur content of about 2.45 weight per cent.

3. A soluble oil blend comprising a mixture of the following ingredients:

Constituent: Weight percent Sodium mahogany sulfonate 9.050.0 Diethylene glycol 0.5- 2.5 Water 0.25- 2.5 Phenol extract 50.0-90.0 Mid-Continent solvent refined neutral oil 0.025.0

said phenol extract being obtained from the solvent extraction of 21 Mid-Continent neutral lubricating oil by treatment with a solvent which removes as an extract phase a predominance of aromatic hydrocarbons, said soluble oil blend being characterized by having a neutralization value ranging from a base member of 6.0 to an acid number of 3.0 as measured by the ASTM 1948 method and further characterized by its stability when emulsified with both hard and soft water for use as a cutting oil lubricant.

4. A soluble oil blend in accordance with claim 3 in which the phenol extract has an 'API gravity of about 13.3, a viscosity at .F. of about 340 SUS, a viscosity index of about 32, a pour point of +35 R, a carbon residue of about 0.13 and a total sulfur content of about 2.45 weight percent.

5. A soluble oil blend consisting of a mixture of the following constituents:

Constituent: Weight percen Sodium mahogany sulfonate 11.5 Diethylene glycol 1.5 Water 1.5 Phenol extract (API gravity 13.3", vis/100 F.

340 SUS) 85.5

Constituent: Weight percen Sodium mahogany sulfonate 11.5 Diethylene glycol 1.5 Water 1.5 Phenol extract (API gravity 13.3", Vis/100 F. 340 SUS) 1.5 Mid-Continent solvent refined neutral oil 21.0

Constituent: Weight percent Sodium mahogany sulfonate 11.5 Diethylene glycol 1.5 Water 1.5 Potassium hydroxide 0.32

Phenol extract (API gravity 13.3 Vis/ 100 F.

340 SUS) 85.18

said phenol extract being obtained from the solvent extraction of a Mid-Continent neutral lubricating oil by treatment with a solvent which removes as an extract phase a predominance of aromatic hydrocarbons, said soluble oil blend being characterized by having a neutralization value ranging from a base number of 6.0 to an acid number of 3.0 as measured by the ASTM 1948 method and further characterized by its stability when emulsified with both hard and soft water for use as a cutting oil lubricant.

I 8. A soluble oil blend consisting of a mixture of the following ingredients:

Constituent: Weight percent Sodium mahogany sulfonate 6.5 Sodium resinate 5.0 Diethylene glycol 1.5 Water 1.5 Phenol extract (API gravity 13.3, Vis/100" F.

340 SUS) 64.5 Mid-Continent solvent refined neutral oil 25.0

said phenol extract being obtained from the solvent extraction of a Mid-Continent neutral lubricating oil by treatment with a solvent which removes, as the extract phase, a predominance of aromatic hydrocarbons, said soluble oil blend being characterized by having a neutralization value ranging from a base number of 6.0 to an acid number of 3.0 as measured by the ASTM 1948 method and further characterized by its stability when emulsified with both hard and soft water for use as a cutting oil lubricant.

9. A soluble oil blend in accordance with claim 8 in which the phenol extract has an API gravity of about 13.3, a viscosity at 100 F. of about 340 SUS, a viscosity index of about -32, a pour point of +35 F., a carbon residue of about 0.13 and a total sulfur content of about 2.45 weight per cent.

10. A soluble oil blend consisting of a mixture of the following ingredients:

Phenol extract (API gravity 13.3 Vis/ 100 F.

340 SUS) 85.18

said phenol extract being obtained from the solvent ex traction of a Mid-Continent neutral lubricating oil by treatment with a solvent which removes as an extract phase a predominance of aromatic hydrocarbons, said soluble oil blend being characterized by having a neutralization value ranging from a base number of 6.0 to an acid number of 3.0 as measured by the ASTM 1948 method and further characterized by its stability when emulsified with both hard and soft water for use as a cutting oil lubricant.

11. A soluble oil blend in accordance with claim 10 in which the phenol extract has an API gravity of about 13.3, a viscosity at F. of about 340 SUS, a viscosity index of about 32, a pour point of +35 F., a carbon residue of about 0.13 and a total sulfur content of about 2.4-5 weight per cent.

References Cited in the file of this patent UNITED STATES PATENTS Asphaltic Products from Petroleum Extracts, article by P. V. McKinney et al., I and E Chem., 37 (2), February 1945. 

1. A SOLUBLE OIL BLEND CONSISTING OF A MIXTURE OF THE FOLLOWING INGREDIENTS: 